Prismatic secondary battery

ABSTRACT

A prismatic secondary battery in which a deformation plate becoming deformed when a pressure inside the battery becomes equivalent to or higher than a predetermined value is disposed in a conductive path between a positive electrode plate and a positive electrode terminal. A positive electrode collector electrically connected to the positive electrode plate includes a collector body portion disposed on an electrode body side of the deformation plate, a collector connection that extends from an end of the collector body portion in a longitudinal direction of a sealing plate towards the sealing plate, and a lead portion that extends from the collector connection in the longitudinal direction of the sealing plate. A positive electrode tab portion is connected to the lead portion.

CROSS REFERENCE TO RELATED APPLICATIONS

The present invention application claims priority to Japanese Patent Application No. 2015-191449 filed in the Japan Patent Office on Sep. 29, 2015, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to a prismatic secondary battery.

Description of Related Art

Secondary batteries such as alkaline secondary batteries and nonaqueous electrolyte secondary batteries are used in power sources for driving electric vehicles (EV), hybrid electric vehicles (HEV, PHEV), and the like. In such applications, since a high capacity or a high input characteristic is required, a battery pack in which a plurality of prismatic secondary batteries are connected in series or in parallel is used.

In such prismatic secondary batteries, a battery case is formed by a bottomed tubular prismatic outer package including an opening and a sealing plate that seals the opening. The battery case accommodates therein an electrode body including positive electrode plates, negative electrode plates, and separators, and an electrolyte. A positive electrode terminal and a negative electrode terminal are installed in the sealing plate. The positive electrode terminal is electrically connected to the positive electrode plates through a positive electrode collector, and the negative electrode terminal is electrically connected to the negative electrode plates through a negative electrode collector.

The positive electrode plate includes a positive electrode core body made of metal and a positive electrode active material layers formed on the surface of the positive electrode core body. A positive electrode core body exposed portion, on which no positive electrode active material layers is formed, is formed in a portion of the positive electrode core body. Furthermore, the positive electrode collector is connected to the positive electrode core body exposed portion. Furthermore, the negative electrode plate includes a negative electrode core body made of metal and a negative electrode active material layer formed on the surface of the negative electrode core body. A negative electrode core body exposed portion, on which no negative electrode active material layer is formed, is formed in a portion of the negative electrode core body. Furthermore, the negative electrode collector is connected to the negative electrode core body exposed portion.

For example, Japanese Published Unexamined Patent Application No. 2009-032640 (Patent Document 1) proposes a prismatic secondary battery using a wounded electrode body including a wounded positive electrode core body exposed portion at one end portion and a wound negative electrode core body exposed portion at the other end portion. Furthermore, Japanese Published Unexamined Patent Application No. 2008-226625 (Patent Document 2) proposes a prismatic secondary battery that uses an electrode body provided with a positive electrode core body exposed portion and a negative electrode core body exposed portion at one end portion.

BRIEF SUMMARY OF THE INVENTION

Development of on-vehicle secondary batteries, particularly, secondary batteries used in EVs and PHEVs that have a higher energy density and a larger battery capacity are awaited. In the case of the prismatic secondary battery disclosed in Patent Literature 1 described above, spaces such as left and right spaces in which the wound positive electrode core body exposed portion and the wound negative electrode core body exposed portion are disposed and an upper space between the sealing plate and the wound electrode body are required in the battery case. Such a requirement is a factor hindering the increase in energy density of the second battery.

Conversely, as is the case of the prismatic secondary battery disclosed in Patent Literature 2, when the electrode body provided with the positive electrode core body exposed portion and the negative electrode core body exposed portion at one end portion is used, it will be easier to obtain a prismatic secondary battery with a high energy density.

However, development of a secondary battery that not only has a higher energy density, but that is easy to assemble and has a reliable and high current collecting structure is awaited.

An object of the present disclosure is to provide a highly reliable prismatic secondary battery that is high in energy density and capacity.

According to an aspect of the present disclosure, a prismatic secondary battery includes an electrode body that includes a positive electrode plate and a negative electrode plate, an outer package that includes an opening and that houses the electrode body, a sealing plate that seals the opening, a terminal electrically connected to the positive electrode plate or the negative electrode plate, and a collector electrically connected to the positive electrode plate or the negative electrode plate, and the terminal. The electrode body includes positive electrode tab portions and negative electrode tab portions that are stacked on a sealing plate side, and a deformation plate provided in a conductive path between the positive electrode plate or the negative electrode plate and the terminal, the deformation plate being deformed when a pressure inside the battery becomes equivalent to or above a predetermined value. The collector includes a collector body portion disposed on an electrode body side of the deformation plate, a collector connection that extends from an end portion of the collector body portion in a longitudinal direction of the sealing plate towards the sealing plate, and a lead portion that extends from the collector connection in the longitudinal direction of the sealing plate. The collector body portion is connected to the deformation plate, the positive electrode tab portion or the negative electrode tab portion is connected to the lead portion, and the conductive path is cut off upon deformation of the deformation plate.

With the above configuration, the prismatic secondary battery not only becomes high in energy density but becomes highly reliable as well.

Desirably, the lead portion is disposed substantially perpendicular to the sealing plate. Note that herein, substantially perpendicular refers to a range that is plus 20° to minus 20° with respect to 90°.

Desirably, the collector body portion includes a narrow width portion in an area adjacent to the collector connection, the narrow width portion having a width in a short direction of the sealing plate that is smaller than a width in the short direction of the sealing plate where the connection with the deformation plate is formed.

Desirably, a rate between the width of the portion of the collector body portion where the connection with the deformation plate is formed in the short direction of the sealing plate and a width of the collector body portion plate in the short direction of the sealing plate is 0.2 to 0.8.

Desirably, a length of the narrow width portion in the longitudinal direction of the sealing plate is three times or more with respect to a thickness of the narrow width portion.

Desirably, a narrow width portion is disposed substantially parallel to the sealing plate. Note that substantially perpendicular refers to an inclination angle of the narrow width portion being plus 20° to minus 20° with respect to the sealing plate.

Desirably, the collector connection includes a portion in which a length in a direction perpendicular to the sealing plate increases from a center towards an outer side of the collector connection in a short direction of the sealing plate.

Desirably, when the collector is unfolded, a slit is formed between the collector body portion and the collector connection, and the slit is inclined 20 to 80° with respect to the longitudinal direction of the sealing plate.

Desirably, an end portion of the lead portion on the electrode body side is positioned on the electrode body side with respect to the end portion of the collector body portion on the electrode body side.

The present disclosure is capable of providing a highly reliable prismatic secondary battery that is high in energy density and capacity.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of a prismatic secondary battery according to an exemplary embodiment.

FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1.

FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2.

FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2.

FIG. 5 is a cross-sectional view taken along line V-V in FIG. 2.

FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 2.

FIGS. 7A and 7B are plan views of a positive electrode plate and a negative electrode plate according to the exemplary embodiment.

FIG. 8 is a plan view of a stacked electrode body according to the exemplary embodiment.

FIG. 9 is a cross-sectional view of a portion in the vicinity of a current breaking mechanism in a longitudinal direction of the sealing plate.

FIG. 10 is a cross-sectional view of a portion in the vicinity of the current breaking mechanism in a short direction of the sealing plate.

FIG. 11 is a plan view of a positive electrode collector before bending used in the exemplary embodiment.

FIGS. 12A to 12C are diagrams illustrating the positive electrode collector after bending used in the exemplary embodiment.

FIG. 13 is a plan view of a negative electrode collector before bending used in the exemplary embodiment.

FIG. 14 is a diagram illustrating a surface of a sealing plate on an inner side of the battery in which the positive electrode collector and the negative electrode collector have been installed.

FIG. 15 is a side view of a sealing plate in which the positive electrode collector and the negative electrode collector have been installed.

FIG. 16 is a diagram of a prismatic secondary battery according to a first modification, corresponding to FIG. 15.

FIG. 17 is a cross-sectional view of the vicinity of the connection between the lead portions of the positive electrode collector and the positive electrode tab portions of the prismatic secondary battery according to the first modification taken in the short direction of the sealing plate.

FIG. 18 is a plan view of the negative electrode collector before bending used in the prismatic secondary battery according to the second modification.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a configuration of a prismatic secondary battery 20 according to an exemplary embodiment will be described. Note that the present disclosure is not limited to the following exemplary embodiment.

As illustrated in FIGS. 1 to 6, the prismatic secondary battery 20 includes a prismatic outer package 1 that has an opening, and a sealing plate 2 that seals the opening. The prismatic outer package 1 and the sealing plate 2 are desirably made of metal and, for example, may be made of aluminum or an aluminum alloy. The prismatic outer package 1 includes a bottom 1 a, a pair of large-area side walls 1 b, and a pair of small-area side walls 1 c. The prismatic outer package 1 is a bottomed and tubular outer package having a rectangular shape and includes the opening at a position facing the bottom 1 a. A stacked electrode body 3 in which a plurality of positive electrode plates 4 and a plurality of negative electrode plates 5 are stacked with separators interposed therebetween are accommodated in the prismatic outer package 1 together with an electrolyte.

Each positive electrode plate 4 includes a positive electrode core body made of metal and a positive electrode active material layer 4 a that include a positive electrode active material formed on the positive electrode core body. Each positive electrode plate 4 includes, at one of its ends, a positive electrode core body exposed portion 4 b in which the positive electrode core body is exposed. Note that, desirably, an aluminum foil or an aluminum alloy foil is used for the positive electrode core body. Each negative electrode plate 5 includes a negative electrode core body made of metal and a negative electrode active material layer 5 a that include a negative electrode active material formed on the negative electrode core body. Each negative electrode plate 5 includes, at one of its ends, a negative electrode core body exposed portion 5 b in which the negative electrode core body is exposed. Note that, desirably, a copper foil or a copper alloy foil is used for the negative electrode core body. In the prismatic secondary battery 20, each positive electrode core body exposed portion 4 b constitutes a positive electrode tab portion 4 c, and each negative electrode core body exposed portion 5 b constitutes a negative electrode tab portion 5 c.

At an end portion of the electrode body 3 on the sealing plate 2 side, positive electrode tab portions 4 c are disposed in a stacked state and the negative electrode tab portions Sc are disposed in a stacked state. A positive electrode collector 6 is connected to the stacked positive electrode tab portions 4 c. Furthermore, a positive electrode terminal 7 is electrically connected to the positive electrode collector 6. A negative electrode collector 8 is connected to the stacked negative electrode tab portions Sc. Furthermore, a negative electrode terminal 9 is electrically connected to the negative electrode collector 8. A pressure-sensitive current breaking mechanism 40 is provided in the conductive path between the positive electrode plates 4 and the positive electrode terminal 7. The current breaking mechanism 40 is activated when the pressure inside the battery becomes equivalent to or higher than a predetermined value, and the current is cut off by cutting off the conductive path between the positive electrode plates 4 and the positive electrode terminal 7. Note that the pressure-sensitive current breaking mechanism 40 may be provided in the conductive path between the negative electrode plates 5 and the negative electrode terminal 9.

As illustrated in FIGS. 2 and 4, a resin member 60 serving as a holding member holding a metal member 61 is connected to a battery inner surface of the sealing plate 2. The resin member 60 and the sealing plate 2 are fitted and connected to each other at a fitting portion 90. The positive electrode tab portions 4 c are bundled at two positions and form a first positive electrode tab group 4 x and a second positive electrode tab group 4 y. The metal member 61 is disposed between the first positive electrode tab group 4 x and the second positive electrode tab group 4 y. Lead portions 6 c are each disposed on an outer surface side of the first positive electrode tab group 4 x and the second positive electrode tab group 4 y.

As illustrated in FIGS. 2 and 6, a resin member 80 holding a metal member 81 is connected to the battery inner surface of the sealing plate 2. The resin member 80 and the sealing plate 2 are fitted and connected to each other at a fitting portion 91. The negative electrode tab portions 5 c are bundled at two positions and form a first negative electrode tab group 5 x and a second negative electrode tab group 5 y. The metal member 81 is disposed between the first negative electrode tab group 5 x and the second negative electrode tab group 5 y. Lead portions 8 c are each disposed on an outer surface side of the first negative electrode tab group 5 x and the second negative electrode tab group 5 y.

Note that the holding member holding the metal member is desirably a member that has an electrical insulation property. Furthermore, the holding member is, desirably, a resin member or a ceramic member.

The positive electrode terminal 7 is attached to the sealing plate 2 in an electrically insulated state with respect to the sealing plate 2 with an inner side insulating member 10 and an outer side insulating member 11. Furthermore, the negative electrode terminal 9 is attached to the sealing plate 2 in an electrically insulated state with respect to the sealing plate 2 with an inner side insulating member 12 and an outer side insulating member 13. The inner side insulating members 10 and 12 and the outer side insulating members 11 and 13 are desirably made of resin. A terminal through-hole 7 x is provided in the positive electrode terminal 7, and the terminal through-hole 7 x is sealed with a terminal plug 7 y.

The electrode body 3 is accommodated inside the prismatic outer package 1 while being covered by an insulation sheet 14. Desirably, the insulation sheet 14 is a resin sheet folded in a box shape or a bag-shaped resin sheet. The sealing plate 2 is joined to an opening edge portion of the prismatic outer package 1 by, for example, laser welding. The sealing plate 2 includes an electrolyte injection hole 15, and the electrolyte injection hole 15 is sealed with a sealing plug 16 after injection of the electrolyte. A gas discharge valve 17 is formed in the sealing plate 2. The gas discharge valve 17 is activated when the pressure inside the battery becomes equivalent to or higher than a predetermined value and is for discharging gas inside the battery to the outside of the battery. Note that the pressure in which the gas discharge valve 17 is activated is set higher than the pressure in which the current breaking mechanism 40 is activated.

A method for manufacturing the prismatic secondary battery 20 will be described next.

Fabrication of Positive Electrode Plate

A positive electrode shiny containing lithium-nickel-cobalt-manganese composite oxide as a positive electrode active material, polyvinylidene fluoride (PVdF) as a binding agent, a carbon material as a conductive material, and N-methylpyrrolidone (NMP) is fabricated. The positive electrode slurry is coated on both surfaces of a rectangular aluminum foil that is 15 μm thick and that serves as the positive electrode core body. Subsequently, by drying the above, the N-methylpyrrolidone in the positive electrode slurry is removed and the positive electrode active material layers are formed on the positive electrode core body. Subsequently, a compression process is performed to compress the positive electrode active material layers to a predetermined thickness. The positive electrode plate obtained in the above manner is cut into a predetermined shape.

Fabrication of Negative Electrode Plate

A negative electrode shiny containing graphite as a negative electrode active material, styrene-butadiene rubber (SBR) as the binding agent, carboxymethyl cellulose (CMC) as a thickener, and water is fabricated. The negative electrode slurry is coated on both surfaces of a rectangular copper foil that is 8 μm thick and that serves as the negative electrode core body. Subsequently, by drying the above, the water in the negative electrode slurry is removed and the negative electrode active material layers are formed on the negative electrode core body. Subsequently, a compression process is performed to compress the negative electrode active material layers to a predetermined thickness. The negative electrode plate obtained in the above manner is cut into a predetermined shape.

FIG. 7A is a plan view of a positive electrode plate 4 after cutting, and FIG. 7B is a plan view of a negative electrode plate 5 after cutting. The positive electrode plate 4 includes rectangular areas that are positive electrode active material layers 4 a formed on both surfaces of the positive electrode core body, and the positive electrode core body exposed portion 4 b serving as the positive electrode tab portion 4 c is formed on one side of the positive electrode plate 4. The negative electrode plate 5 includes rectangular areas that are negative electrode active material layers 5 a formed on both surfaces of the negative electrode core body, and the negative electrode core body exposed portion 5 b serving as the negative electrode tab portion Sc is formed on one side of the negative electrode plate 5. Note that the size of the positive electrode plate 4 is slightly smaller than the size of the negative electrode plate 5. Desirably, an insulating layer or a protective layer 4 d that has an electric resistance that is higher than that of the positive electrode core body is provided at the base portion of the positive electrode tab portion 4 c. Note that conductive members other than the above may be connected to the positive electrode core body exposed portion 4 b or the negative electrode core body exposed portion 5 b to serve as the positive electrode tab portion 4 c or the negative electrode tab portion Sc, respectively.

Fabrication of Stacked Electrode Body

The stacked electrode body 3 is fabricated by fabricating 100 pieces of positive electrode plates 4 and 101 pieces of negative electrode plates 5 with the above methods and by stacking each positive electrode plate 4 and each negative electrode plate 5 on each other with a rectangular polyolefin separator therebetween. As illustrated in FIG. 8, the stacked electrode body 3 is fabricated such that the positive electrode tab portions 4 c of the positive electrode plates 4 and the negative electrode tab portions Sc of the negative electrode plates 5 are stacked at one end portion of the electrode body 3. Desirably, separators are disposed on both outer surfaces of the stacked electrode body 3 and the electrode plates and the separators are fixed with tapes 18 and the like in a stacked state. Alternatively, an adhesion layer may be provided on each separator such that the separators and the positive electrode plates 4, and the separators and the negative electrode plates 5 are adhered to each other. Note that the size of the separator in plan view is the same or larger than the size of the negative electrode plate 5. Each positive electrode plate 4 may be disposed between two separators and after heat welding the outer peripherals of the separators, each of the positive electrode plates 4 and each of the negative electrode plates 5 may be stacked on each other.

Attaching Positive Electrode Terminal and Current Breaking Mechanism to Sealing Plate

FIG. 9 is a cross-sectional view of a portion in the vicinity of the current breaking mechanism 40 in the longitudinal direction of the sealing plate 2. FIG. 10 is a cross-sectional view of a portion in the vicinity of the current breaking mechanism 40 in the short direction of the sealing plate 2.

A positive electrode terminal mounting hole 2 a serving as a through-hole is formed in the sealing plate 2. The outer side insulating member 11 is disposed on the battery outer surface side of the positive electrode terminal mounting hole 2 a, and the inner side insulating member 10 and a conductive member 41 are disposed on the battery inner surface side. Furthermore, the positive electrode terminal 7 is inserted from the outer side of the battery through the through-holes formed in the outer side insulating member 11, the sealing plate 2, the inner side insulating member 10, and the conductive member 41, and the tip of the positive electrode terminal 7 is riveted on the conductive member 41. Note that the riveted portion of the tip of the positive electrode terminal 7 is, desirably, further welded to the conductive member 41.

Desirably, the conductive member 41 has a cup-shape that includes an opening portion 41 x open towards the electrode body 3 side. The conductive member 41 includes a base portion 41 a that is disposed parallel to the sealing plate 2, and a cylindrical portion 41 b that extends from the base portion 41 a towards the electrode body 3 side. The cylindrical portion 41 b may have a cylindrical shape or may be a rectangular tubular portion. The conductive member 41 is made of metal and, desirably, is made of aluminum or an aluminum alloy. The positive electrode terminal 7 is connected to the base portion 41 a. Note that the positive electrode terminal 7 and the conductive member 41 may be an integral component. In such a case, the positive electrode terminal 7 is inserted into the through-holes of the components from the inner side of the battery and is riveted on the outer side of the battery.

The inner side insulating member 10 includes an insulating member body portion 10 a disposed between the sealing plate 2 and the base portion 41 a of the conductive member 41, a pair of insulating member first side walls 10 b that extend from the two end portions of the insulating member body portion 10 a in the short direction of the sealing plate 2 towards the electrode body 3 side, and a pair of insulating member second side walls 10 c that extend from the two end portions of the insulating member body portion 10 a in the longitudinal direction of the sealing plate 2 towards the electrode body 3 side. A protrusion 10 d is formed on the outer surface of each insulating member first side wall 10 b.

Subsequently, a deformation plate 42 is disposed so as to close the opening portion 41 x of the conductive member 41 on the electrode body 3 side, and the outer peripheral edge of the deformation plate 42 is joined to the conductive member 41 by laser welding or the like. With the above, the opening portion 41 x of the conductive member 41 on the electrode body 3 side is sealed in an airtight manner. The deformation plate 42 is made of metal and, desirably, is made of aluminum or an aluminum alloy. The shape of the deformation plate 42 is desirably the same as that of the opening portion 41 x of the conductive member 41. In the prismatic secondary battery 20, the deformation plate 42 has a circular shape in plan view.

Subsequently, a dielectric plate 43 serving as a first insulating member is disposed on the surface of the deformation plate 42 on the electrode body 3 side. The dielectric plate 43 includes a dielectric plate body portion 43 a disposed between the deformation plate 42 and a collector body portion 6 a of the positive electrode collector 6, and a pair of dielectric plate first side walls 43 b that extend from two edge portions of the dielectric plate body portion 43 a in a short direction of the sealing plate 2 towards the sealing plate 2 side. A dielectric plate through-hole 43 c, a first projection 43 d 1, a second projection 43 d 2, a third projection 43 d 3, and a fourth projection 43 d 4 are formed in the dielectric plate body portion 43 a. Furthermore, recesses 43 e are formed on the inner surface of the dielectric plate first side walls 43 b.

A projection 42 a formed in the middle portion of the deformation plate 42 is inserted into the dielectric plate through-hole 43 c formed in the dielectric plate body portion 43 a. Furthermore, the inner surfaces of the dielectric plate first side walls 43 b are disposed so as to face the outer surfaces of the insulating member first side walls 10 b. Furthermore, by fitting the protrusions 10 c and the recesses 43 e to each other, the insulating member 10 and the dielectric plate 43 are connected to each other. Note that the recesses 43 e may be through-holes.

Flange portions 41 c are provided on the end portions of the conductive member 41 on the electrode body 3 side. Furthermore, hooking and fixing portions that can be hooked to the flange portions 41 c of the conductive member 41 are desirably provided on the surface of the dielectric plate body portion 43 a on the sealing plate 2 side. With the above, the dielectric plate 43 is fixed to the conductive member 41.

Positive Electrode Collector

Referring to FIGS. 11 and 12A to 12C, a configuration of the positive electrode collector 6 will be described. FIG. 11 is a plan view of the positive electrode collector 6 before bending, and illustrates a surface thereof on the electrode body 3 side. FIGS. 12A to 12C are diagrams of the positive electrode collector 6 after bending. FIG. 12A is a diagram of the positive electrode collector 6 viewed from the electrode body 3 side, FIG. 12B is a side view of the positive electrode collector 6 viewed from the gas discharge valve 17 side in the longitudinal direction of the sealing plate 2, and FIG. 12C is a side view of the positive electrode collector 6 viewed in the short direction of the sealing plate 2. Note that in FIG. 11, the positive electrode collector 6 is bent at the dotted line portions.

The positive electrode collector 6 includes a collector body portion 6 a, a collector connection 6 b provided at an end portion of the collector body portion 6 a, and the pair of lead portions 6 c provided at two edge portions of the collector connection 6 b. As illustrated in FIGS. 12A to 12C, the collector connection 6 b is provided at the end portion of the collector body portion 6 a in the longitudinal direction of the sealing plate 2. Furthermore, the collector connection 6 b is provided so as to extend from the collector body portion 6 a towards the sealing plate 2. The pair of lead portions 6 c are provided at the two edge portions of the collector connection 6 b in the short direction of the sealing plate 2. Furthermore, the pair of lead portions 6 c are provided so as to extend from the collector connection 6 b in the longitudinal direction of the sealing plate 2. Moreover, each of the pair of lead portions 6 c is disposed substantially perpendicular to the sealing plate 2. Note that herein, substantially perpendicular refers to a range that is plus 20° to minus 20° with respect to 90°, that is, substantially perpendicular refers to a range of 70° to 110°.

A through-hole 6 d for connection is formed in the collector body portion 6 a, and a thin wall portion 6 e is formed around the through-hole 6 d for connection. Furthermore, an annular groove portion 6 f is provided inside the thin wall portion 6 e so as to surround the through-hole 6 d for connection. The thickness (the residual thickness) of the groove portion 6 f is smaller than that of the thin wall portion 6 e. Note that the annual groove portion 6 f is a fragile portion and is broken upon deformation of the deformation plate 42. In other words, the fragile portion is the portion to be broken. Note that since it is only sufficient that the conductive path is cut off upon breakage of the fragile portion, both of the thin wall portion 6 e and the groove portion 6 f do not have to be provided. Only the thin wall portion 6 e or only the groove portion 6 f may be provided. Alternatively, the connection between the deformation plate 42 and the collector body portion 6 a may be a fragile portion without providing the thin wall portion 6 e of the groove portion 6 f. Alternatively, the fragile portion, such as the thin wall portion or a groove portion, may be provided in the deformation plate 42.

Note that the through-hole 6 d for connection is not an essential configuration, and the thin wall portion provided in the collector body portion 6 a may be connected to the deformation plate 42.

A first through-hole 6 y 1 for fixing, a second through-hole 6 y 2 for fixing, a third through-hole 6 y 3 for fixing, and a fourth through-hole 6 y 4 for fixing are provided in the collector body portion 6 a. A recess is provided around each of the first through-hole 6 y 1 for fixing, the second through-hole 6 y 2 for fixing, the third through-hole 6 y 3 for fixing, and the fourth through-hole 6 y 4 for fixing.

The collector body portion 6 a of the positive electrode collector 6 includes a narrow width portion 6 a 1 at an area adjacent to the collector connection 6 b. A width of the narrow width portion 6 a 1 in the short direction of the sealing plate 2 is smaller than a width W1 of the collector body portion 6 a in the short direction of the sealing plate 2 at a portion where the connection with the deformation plate 42 is formed. Note that when the width of the narrow width portion 6 a 1 in the short direction of the sealing plate 2 is Wx, the value of Wx/W1 is preferably 0.2 to 0.8 and, more preferably is 0.3 to 0.7, and most preferably is 0.3 to 0.6. Furthermore, the length of the area in the longitudinal direction of the sealing plate 2 including the width Wx in which the value of Wx/W1 is 0.2 to 0.8 is preferably 2 mm or more and, more preferably is 3 mm or more. Note that the length of the area in the longitudinal direction of the sealing plate 2 including the width Wx in which the value of Wx/W1 is 0.2 to 0.8 is preferably 20 mm or less and, more preferably, is 10 mm or less.

Furthermore, desirably, an area having a substantially uniform (±10% in width, for example) in the short direction of the sealing plate 2 is provided in the narrow width portion 6 a 1. As illustrated in FIG. 12A, a length L1 of the area having a substantially uniform width is preferably 2 mm or more and, more preferably, is 3 mm or more in the longitudinal direction of the sealing plate 2. Note that the width Wx in the narrow width portion 6 a 1 does not have to be uniform.

As illustrated in FIG. 12A, a length L2 of the narrow width portion 6 a in the longitudinal direction of the sealing plate 2 between a fixed portion that is positioned nearest to the collector connection 6 b side (the fourth through-hole 6 y 4 for fixing of a fourth fixed portion 70 d) among the fixed portions of the collector body portion 6 a of the positive electrode collector 6 and the fixed portions of the dielectric plate 43, and the boundary between the collector body portion 6 a and the collector connection 6 b is preferably 2 mm or more, and more preferably is 3 mm or more. Furthermore, when the thickness (a thickness in a direction perpendicular to the sealing plate 2) of the narrow width portion 6 a 1 is T (mm), L2 (mm) is preferably larger than 3T (mm).

The collector body portion 6 a of the positive electrode collector 6 includes, in the narrow width portion 6 a 1, an area 6 a 2 in which the width thereof in the short direction of the sealing plate 2 becomes gradually smaller. The collector connection 6 b of the positive electrode collector 6 includes, at both end sides in the short direction of the sealing plate 2, areas 6 b 1 in which the lengths thereof become gradually large in the direction perpendicular to the sealing plate 2.

As illustrated in FIG. 12C, in the direction perpendicular to the sealing plate 2, the collector body portion 6 a of the positive electrode collector 6 is positioned on the electrode body 3 side with respect to the end portions of the lead portions 6 c on the sealing plate 2 side, and is positioned on the sealing plate 2 side with respect to the end portions of the lead portions 6 c on the electrode body 3 side.

As illustrated in FIG. 11, in the unfolded positive electrode collector 6, slits 30 are formed between the collector body portion 6 a and the collector connection 6 b. Furthermore, desirably, the slits 30 are each inclined 20 to 80° with respect to the longitudinal direction of the sealing plate 2. With the above, the collector body portion 6 a and the collector connection 6 b will not interfere with each other and the internal resistance of the positive electrode collector becomes small.

Attaching Positive Electrode Collector

The positive electrode collector 6 described above is disposed on the surface of the dielectric plate 43 on the electrode body 3 side. In so doing, the first projection 43 d 1, the second projection 43 d 2, the third projection 43 d 3, and the fourth projection 43 d 4 formed in the dielectric plate 43 are respectively inserted into the first through-hole 6 y 1 for fixing, the second through-hole 6 y 2 for fixing, the third through-hole 6 y 3 for fixing, and the fourth through-hole 6 y 4 for fixing formed in the positive electrode collector 6. Subsequently, by expanding the diameters of the tips of the first projection 43 d 1, the second projection 43 d 2, the third projection 43 d 3, and the fourth projection 43 d 4, the positive electrode collector 6 is fixed to the dielectric plate 43. With the above, a first fixed portion 70 a, a second fixed portion 70 b, a third fixed portion 70 c, and a fourth fixed portion 70 d are formed. Note that the projections may be press-fitted into the through-holes for fixing.

Gas is sent in through the terminal through-hole 7 x formed in the positive electrode terminal 7 from the outer side of the battery, such that the deformation plate 42 is urged against the collector body portion 6 a of the positive electrode collector 6. In the above state, the edge portion of the through-hole 6 d for connection provided in the collector body portion 6 a of the positive electrode collector 6 and the deformation plate 42 are joined together by laser welding or the like. Note that the through-hole 6 d for connection is not an essential configuration and a collector body portion 6 a that has no through-hole 6 d for connection may be joined to the deformation plate 42. The terminal through-hole 7 x is sealed with the terminal plug 7 y.

The positive electrode collector 6 to which bending has been performed in advance may be connected to the dielectric plate 43 and the deformation plate 42. Alternatively, bending may be performed on the positive electrode collector 6 after the positive electrode collector 6 has been connected to the dielectric plate 43 and the deformation plate 42.

Attaching Negative Electrode Terminal to Sealing Plate Negative Electrode Collector

A configuration of the negative electrode collector 8 will be described. FIG. 13 is a plan view of the negative electrode collector 8 before bending, and illustrates a surface thereof on the electrode body 3 side. The negative electrode collector 8 includes a collector body portion 8 a, a pair of collector connections 8 b provided at two ends of the collector body portion 8 a, and the pair of lead portions Sc provided in the pair of collector connections 8 b. In the negative electrode collector 8 to which bending has been performed, the pair of collector connections 8 b are disposed at both ends of the collector body portion 8 a in the short direction of the sealing plate 2 so as to extend from the collector body portion 8 a towards the electrode body 3. The pair of lead portions 8 c are disposed so as to extend in the longitudinal direction of the sealing plate 2 from the pair of collector connections 8 b. A through-hole 8 d into which the negative electrode terminal 9 is inserted is provided in the collector body portion 8 a. A recess is formed around the through-hole 8 d.

A negative electrode terminal mounting hole 2 b serving as a through-hole is formed in the sealing plate 2. The outer side insulating member 13 is disposed on the outer surface side of the negative electrode terminal mounting hole 2 b, and the inner side insulating member 12 and the collector body portion 8 a of the negative electrode collector 8 are disposed on the inner surface side. Furthermore, the negative electrode terminal 9 is inserted from the outer side of the battery through the through-holes formed in the outer side insulating member 13, the sealing plate 2, the inner side insulating member 12, and collector body portion 8 a of the negative electrode collector 8, and the tip of the negative electrode terminal 9 is riveted on the negative electrode collector 8. Furthermore, the riveted portion of the negative electrode terminal 9 is welded to the negative electrode collector 8.

Subsequently, bending is performed on the negative electrode collector 8 such that the pair of lead portions 8 c and the pair of collector connections 8 b are substantially perpendicular to the collector body portion 8 a. Note that the negative electrode collector 8 may be connected to the negative electrode terminal 9 after bending has been performed on the negative electrode collector 8.

Attaching Metal Member and Resin Member to Sealing Plate

A first fitting protrusion 2 c and a second fitting protrusion 2 d are provided in the surface of the sealing plate 2 on the inner side of the battery. A first base end recess 2 e is provided around a base end of the first fitting protrusion 2 c, and a second base end recess 2 f is provided around a base end of the second fitting protrusion 2 d. The first fitting protrusion 2 c is disposed between the positive electrode terminal mounting hole 2 a and the gas discharge valve 17, and the second fitting protrusion 2 d is disposed between the negative electrode terminal mounting hole 2 b and the gas discharge valve 17.

The resin member 60 includes a holding portion 60 a that holds the metal member 61, and a fitting recess 60 b into which the first fitting protrusion 2 c of the sealing plate 2 is fitted. The holding portion 60 a includes a holding through-hole 60 d that extends in the short direction of the sealing plate 2. The metal member 61 has a columnar shape and is disposed inside the holding through-hole 60 d provided in the holding portion 60 a.

The resin member 80 includes a holding portion 80 a that holds the metal member 81, and a fitting recess 80 b into which the second fitting protrusion 2 d of the sealing plate 2 is fitted. The holding portion 80 a includes a holding through-hole 80 d that extends in the short direction of the sealing plate 2. The metal member 81 has a columnar shape and is disposed inside the holding through-hole 80 d provided in the holding portion 80 a. Note that the metal members 61 and 81 are desirably, pillar shaped and are, desirably, columnar or prismatic.

The resin member 60 is connected to the sealing plate 2 by fitting the first fitting protrusion 2 c of the sealing plate 2 to the fitting recess 60 b of the resin member 60 holding the metal member 61. With the above, the fitting portion 90 is formed. Furthermore, the resin member 80 is connected to the sealing plate 2 by fitting the second fitting protrusion 2 d of the sealing plate 2 to the fitting recess 80 b of the resin member 80 holding the metal member 81. With the above, the fitting portion 91 is formed.

Desirably, the shapes of the first fitting protrusion 2 c and the second fitting protrusion 2 d in plan view are each elliptical, oval, rectangular, or a rectangle with rounded corners. With the above, rotation of the resin member 60 or the resin member 80 with respect to the sealing plate 2 can be prevented.

As illustrated in FIG. 4, the resin member 60 includes a contact preventing portion 60 c disposed between the lead portions 6 c of the positive electrode collector 6 and the sealing plate 2. Furthermore, as illustrated in FIG. 6, the resin member 80 includes a contact preventing portion 80 c disposed between the lead portions Sc of the negative electrode collector 8 and the sealing plate 2. The contact preventing portion 60 c or the contact preventing portion 80 c reliably prevents the positive electrode collector 6 or the negative electrode collector 8 from coming in contact with the sealing plate 2.

A thickness of the contact preventing portion 60 c is smaller than a thickness of the holding portion 60 a in the direction perpendicular to the sealing plate 2. Furthermore, the contact preventing portion 60 c is disposed so as to extend towards the large-area side walls 1 b of the prismatic outer package 1 from the holding portion 60 a.

FIG. 14 is a diagram illustrating the surface of the sealing plate 2 on the inner side of the battery to which the positive electrode collector 6, the negative electrode collector 8, the resin member 60 holding the metal member 61, and the resin member 80 holding the metal member 81 are attached. FIG. 15 is a diagram illustrating a side view of the sealing plate 2 to which the positive electrode collector 6, the negative electrode collector 8, the resin member 60 holding the metal member 61, and the resin member 80 holding the metal member 81 are attached. Similar to the resin member 60, the resin member 80 includes the contact preventing portion 80 c and the holding through-hole 80 d.

Connecting Positive Electrode Tab Portions and Positive Electrode Collector to Each Other

A plurality of positive electrode tab portions 4 c are bundled at two positions forming the first positive electrode tab group 4 x and the second positive electrode tab group 4 y. Note that in the first positive electrode tab group 4 x and the second positive electrode tab group 4 y, since the positive electrode tab portions 4 c are fixed to each other, desirably, the positive electrode tab portions 4 c are joined to each other by welding. Alternatively, since the positive electrode tab portions 4 c are fixed to each other, desirably, the positive electrode tab portions 4 c are fixed to each other with a bundling component. For example, a metal or resin bundling component may fix the bundled positive electrode tab portions 4 c while penetrating through the bundled positive electrode tab portions 4 c.

The first positive electrode tab group 4 x is disposed between first lead portions 6 c of the positive electrode collector 6 and the metal member 61. Furthermore, the second positive electrode tab group 4 y is disposed between second lead portions 6 c of the positive electrode collector 6 and the metal member 61. Subsequently, a pair of resistance welding electrodes are disposed on an outer surface side of the first lead portions 6 c and an outer surface side of the second lead portions 6 c. Subsequently, resistance welding is performed while the pair of resistance welding electrodes hold the first lead portions 6 c, the first positive electrode tab group 4 x, the metal member 61, the second positive electrode tab group 4 y, and the second lead portions 6 c in between. With the above, the first lead portions 6 c and the first positive electrode tab group 4 x are joined to each other, and the second lead portions 6 c and the second positive electrode tab group 4 y are joined to each other. In so doing, desirably, the first positive electrode tab group 4 x and the second positive electrode tab group 4 y are each welded to the metal member 61.

Note that before the first positive electrode tab group 4 x and the second positive electrode tab group 4 y are disposed between the pair of lead portions 6 c of the positive electrode collector 6 and the metal member 61, the positive electrode collector 6 is, desirably, unfolded so that the distal ends of the pair of lead portions 6 c are spread outwards.

Connecting Negative Electrode Tab Portions and Negative Electrode Collector to Each Other

A plurality of negative electrode tab portions Sc are bundled at two positions forming the first negative electrode tab group 5 x and the second negative electrode tab group 5 y. Note that similar to the first positive electrode tab group 4 x and the second positive electrode tab group 4 y, the negative electrode tab portions 5 c may be fixed to each other in the first negative electrode tab group 5 x and the second negative electrode tab group 5 y. The first negative electrode tab group 5 x is disposed between first lead portions 8 c of the negative electrode collector 8 and the metal member 81. Furthermore, the second negative electrode tab group 5 y is disposed between second lead portions 8 c of the negative electrode collector 8 and the metal member 81. Subsequently, a pair of resistance welding electrodes are disposed on an outer surface side of the first lead portions 8 c and an outer surface side of the second lead portions 8 c. Subsequently, resistance welding is performed while the pair of resistance welding electrodes hold the first lead portions 8 c, the first negative electrode tab group 5 x, the metal member 81, the second negative electrode tab group 5 y, and the second lead portions Sc in between. With the above, the first lead portions Sc and the first negative electrode tab group 5 x are joined to each other, and the second lead portions Sc and the second negative electrode tab group 5 y are joined to each other. In so doing, desirably, the first negative electrode tab group 5 x and the second negative electrode tab group 5 y are each welded to the metal member 81.

Similar to the positive electrode side, before the first negative electrode tab group 5 x and the second negative electrode tab group 5 y are disposed between the lead portions Sc of the negative electrode collector 8 and the metal member 81, the negative electrode collector 8 is, desirably, unfolded so that the distal ends of the pair of lead portions Sc are spread outwards.

Assembling Prismatic Secondary Battery

The electrode body 3 that is connected to the sealing plate 2 is covered with the insulation sheet 14 and is inserted into the prismatic outer package 1. Subsequently, the sealing plate 2 and the prismatic outer package 1 is joined together by laser welding or the like and the opening of the prismatic outer package 1 is sealed. After the above, nonaqueous electrolyte containing an electrolyte solvent and electrolyte salt is injected through the electrolyte injection hole 15 provided in the sealing plate 2. Subsequently, the electrolyte injection hole 15 is sealed with the sealing plug 16.

Prismatic Secondary Battery

In the prismatic secondary battery 20, a current collecting structure is formed by disposing the resin member 60 holding the metal member 61 and the resin member 80 holding the metal member 81 between a power storing portion (a portion in which the positive electrode plates 4 and the negative electrode plates 5 are stacked with the separators in between) of the electrode body 3 and the sealing plate 2. Accordingly, the prismatic secondary battery becomes further higher in energy density. Furthermore, since assembling is facilitated and connection of the members can be performed more easily, the prismatic secondary battery becomes one with a high connection quality and high reliability. Note that it is only sufficient that a metal member and a holding member are provided on either one of the positive electrode side or the negative electrode side.

Furthermore, in the prismatic secondary battery 20, the resin member 60 holding the metal member 61 and the resin member 80 holding the metal member 81 are attached to the sealing plate 2. With such a configuration, the positive electrode tab portions 4 c or the negative electrode tab portions 5 c can be attached in a stable manner to the positive electrode collector 6 or the negative electrode collector 8 after the positive electrode collector 6 or the negative electrode collector 8 has been attached to the sealing plate 2 in advance. Accordingly, the quality of the connection between the positive electrode collector 6 and the electrode tab portions 4 c or the quality of the connection between the negative electrode collector 8 and the negative electrode tab portions Sc becomes higher, and the prismatic secondary battery becomes further high in reliability.

The space required for the collector portion can be made smaller without the need for bending the positive electrode collector 6 or the negative electrode collector 8 after the positive electrode tab portions 4 c or the negative electrode tab portions Sc have been connected to the positive electrode collector 6 or the negative electrode collector 8 by fixing the resin member 60 holding the metal member 61 or the resin member 80 holding the metal member 81 to the sealing plate 2 and by connecting the positive electrode collector 6 or the negative electrode collector 8 to the positive electrode tab portions 4 c or the negative electrode tab portions Sc using the resin member 60 or the resin member 80. Accordingly, load applied to the positive electrode tab portions 4 c or the negative electrode tab portions Sc due to bending or the like, and load applied to the joint portions between the positive electrode collector 6 or the negative electrode collector 8 and the positive electrode tab portions 4 c or the negative electrode tab portions Sc can be suppressed. Accordingly, a highly reliable prismatic secondary battery having not only a high energy density but one in which damage and the like thereto are suppressed can be obtained.

Furthermore, in a case in which the current breaking mechanism 40 is provided between the positive electrode plates 4 and the positive electrode terminal 7, when the resin member 60 holding the metal member 61 is fixed to the sealing plate 2, even if there is force that moves the electrode body 3 inside the prismatic outer package 1, a load being applied to the connection between the deformation plate 42 and the positive electrode collector 6 and to the fragile portion provided in the positive electrode collector 6 can be suppressed. With the above, the prismatic secondary battery becomes more reliable.

The fixed portion between the resin member 60 and the sealing plate 2 is, desirably, disposed on the gas discharge valve 17 side with respect to the positive electrode terminal mounting hole 2 a. Furthermore, the fixing portion between the resin member 60 and the sealing plate 2 is, desirably, disposed on the gas discharge valve 17 side with respect to the end portion of the deformation plate 42 on the gas discharge valve 17 side. Furthermore, the fixed portion between the resin member 80 and the sealing plate 2 is, desirably, disposed on the gas discharge valve 17 side with respect to the negative electrode terminal mounting hole 2 b.

As illustrated in FIG. 9, in the direction perpendicular to the sealing plate 2, a length H1 of the resin member 60 from the surface of the sealing plate 2 on the inner side of the battery to the end portion of the resin member 60 on the electrode body 3 side is, desirably, larger than a length H2 from the surface of the sealing plate 2 on the inner side of the battery to the surface of the collector body portion 6 a on the electrode body 3 side. With the above, even if the electrode body 3 moves towards the sealing plate 2, the power storing portion of the electrode body 3 can be suppressed from coming in contact with the collector body portion 6 a of the positive electrode collector 6. Accordingly, damage can be suppressed from being caused in the connection between the collector body portion 6 a and the deformation plate 42, the fragile portion provided in the collector body portion 6 a of the positive electrode collector 6, or the like. Note that in at least one of the resin member 60 and the resin member 80, in the direction perpendicular to the sealing plate 2, the length from the surface of the sealing plate 2 on the inner side of the battery to the end portion on the electrode body 3 side is, desirably, larger than the length from the surface of the sealing plate 2 on the inner side of the battery to the surface of the collector body portion 6 a on the electrode body 3 side.

Furthermore, desirably, the end portion of the resin member 60 on the electrode body 3 side is positioned on the electrode body 3 side with respect to the surface of the collector body portion 6 a on the electrode body 3 side. With such a configuration, even if the electrode body 3 is moved towards the sealing plate 2 by vibration, an impact, or the like, the electrode body 3 comes in contact with the resin member 60 or the resin member 80 before the collector body portion 6 a of the positive electrode collector 6. Accordingly, damage can be suppressed from being caused in the connection between the collector body portion 6 a and the deformation plate 42, the fragile portion provided in the collector body portion 6 a of the positive electrode collector 6, or the like.

As illustrated in FIGS. 4 and 6, in the short direction of the sealing plate 2, the widths of the end portions of the resin member 60 and the resin member 80 on the electrode body 3 side become smaller from the sealing plate 2 side towards the electrode body 3 side. With the above, the positive electrode tab portions 4 c or the negative electrode tab portions Sc can be prevented from becoming damaged by the resin member 60 or the resin member 80.

As illustrated in FIG. 15, in the direction perpendicular to the sealing plate 2, the distance between the sealing plate 2 and the lead portions 8 c of the negative electrode collector 8 is larger than the distance between the sealing plate 2 and the lead portions 6 c of the positive electrode collector 6. Such a configuration can reliably prevent the negative electrode collector 8 and the sealing plate 2 from coming in contact with each other. With the above, when the sealing plate 2 is made of aluminum or an aluminum alloy, the sealing plate 2 is electrically connected to the negative electrode and formation of a lithium alloy causing corrosion of the sealing plate 2 can be reliably prevented.

As illustrated in FIG. 14, the sealing plug 16 sealing the electrolyte injection hole 15 protrudes on the electrode body 3 side with respect to the surface of the sealing plate 2 on the inner side of the battery. Furthermore, the electrolyte injection hole 15 is formed between the gas discharge valve 17 and the negative electrode terminal mounting hole 2 b. In order to obtain a sealing structure with a high durability, the sealing plug 16 is desirably made of metal. For example, the sealing plug 16 may be a blind rivet and may be made of aluminum or an aluminum alloy. In the prismatic secondary battery 20, the negative electrode tab portions Sc are divided into two and are bundled so as to be structured so that the sealing plug 16 and the negative electrode tab portions Sc do not come close to each other; accordingly, electrical connection between the negative electrode tab portion Sc and the sealing plug 16 can be prevented in a further reliable manner. Furthermore, since the prismatic secondary battery 20 is configured so that the resin member 80 is disposed at a portion opposing the sealing plug 16, electrical connection between the negative electrode tab portion Sc and the sealing plug 16 can be prevented in a further reliable manner. Note that in a case in which the sealing plug 16 is made of aluminum or an aluminum alloy, when the sealing plug 16 and the negative electrode tab portion Sc are electrically connected to each other, the sealing plug 16 is turned into a lithium alloy and may disadvantageously become corroded.

As illustrated in FIGS. 11, 12, and 14, the positive electrode collector 6 includes the collector body portion 6 a, the collector connection 6 b that extends from the end portion of the collector body portion 6 a in the longitudinal direction of the sealing plate 2 towards the sealing plate 2, and the pair of lead portions 6 c that extend in the longitudinal direction of the sealing plate 2 from the collector connection 6 b. With such a configuration, the collector portion can be disposed in the space next to the current breaking mechanism 40 such that the prismatic secondary battery becomes higher in energy density.

Furthermore, the lead portions 6 c are disposed substantially perpendicular to the sealing plate 2. With the above, the connecting work of connecting the lead portions 6 c and the positive electrode tab portions 4 c to each other is facilitated and the quality of the connection can be improved. Accordingly, the prismatic secondary battery becomes more reliable.

The narrow width portion 6 a 1 is formed in the collector body portion 6 a of the positive electrode collector 6 in an area adjacent to the collector connection 6 b. With the above, even if there is force course by impact or a vibration of the battery that makes the electrode body 3 pull the lead portions 6 c of the positive electrode collector 6, the narrow width portion 6 a 1 will absorb the stress such that a load to the connection between the collector body portion 6 a and the deformation plate 42, or to the fragile portion provided in the collector body portion 6 a of the positive electrode collector 6 can be suppressed. Note that in the course of development, the inventors have found that force that moves the lead portions 6 c in the direction perpendicular to the sealing plate 2 tends to be generated more easily and, furthermore, that such force has a large adverse effect on the connection between the collector body portion 6 a and the deformation plate 42 or the fragile portion provided in the collector body portion 6 a of the positive electrode collector 6. Accordingly, it has been found that as is the case of the prismatic secondary battery 20, it is especially effective to provide the narrow width portion 6 a 1 in the collector body portion 6 a. Note that in such a case, the collector body portion 6 a is, desirably, substantially parallel to the sealing plate 2. The inclination of the collector body portion 6 a with respect to the sealing plate 2 is preferably 0°±20° and, more preferably, is 0°±10 degrees.

Note that in the collector body portion 6 a, the narrow width portion 6 a 1 may be slightly inclined (±30° or smaller, for example) with respect to the other portions of the collector body portion 6 a. However, desirably, the narrow width portion 6 a 1 and the other portions of the collector body portion 6 a are flush with each other.

The length of the narrow width portion 6 a 1 in the longitudinal direction of the sealing plate 2 between the fixed portion positioned nearest to the collector connection 6 b side (the fourth through-hole 6 y 4 for fixing of a fourth fixed portion 70 d) among the fixed portions of the collector body portion 6 a of the positive electrode collector 6 and the fixed portions of the dielectric plate 43, and the boundary between the collector body portion 6 a and the collector connection 6 b is preferably 2 mm or more, more preferably is 3 mm or more, and most preferably is 5 mm or more.

When the width of the collector body portion 6 a in the short direction of the sealing plate 2 in the portion where the connection with the deformation plate 42 is formed is W1, the width Wx of the narrow width portion 6 a 1 in the short direction of the sealing plate 2 is set such that Wx/W1 is 0.2 to 0.6. In such a case, desirably, there is a distance of 2 mm or more, more preferably 3 mm or more, and most preferably 5 mm or more in the longitudinal direction of the sealing plate between the fourth through-hole 6 y 4 for fixing (the fixed portion that is positioned nearest to the collector connection 6 b side that is positioned nearest to the collector connection 6 b side among the fixed portions of the collector body portion 6 a of the positive electrode collector 6 and the fixed portions of the dielectric plate 43) and the boundary between the collector body portion 6 a and the collector connection 6 b.

The collector connection 6 b desirably includes portions in which the lengths thereof in the direction perpendicular to the sealing plate 2 increase from the center towards the outer side in the short direction of the sealing plate 2. With the above, load being applied to the connection between the collector body portion 6 a and the deformation plate 42 or to the fragile portion provided in the collector body portion 6 a of the positive electrode collector 6 can be suppressed while increase in internal resistance is suppressed.

Furthermore, desirably, the end portion of the lead portions 6 c of the positive electrode collector 6 on the electrode body 3 side is positioned on the electrode body 3 side with respect to the end portion of the collector body portion 6 a on the electrode body 3 side. With the above, even if the electrode body 3 were to move towards the sealing plate 2, the electrode body 3 can be suppressed from damaging the connection between the collector body portion 6 a and the deformation plate 42 or the fragile portion provided in the collector body portion 6 a of the positive electrode collector 6.

Description of modifications will be given below. Note that in the modifications, components that are the same as those of the prismatic secondary battery 20 described above are denoted with the same reference numerals as those of the prismatic secondary battery 20. Furthermore, portions that are not described in particular may each have the same configuration as that of the prismatic secondary battery 20 described above.

First Modification

In the prismatic secondary battery 20 described above, an example in which the positive electrode collector 6 and the positive electrode tab portions 4 c are connected by resistance welding and in which the negative electrode collector 8 and the negative electrode tab portions 5 c are connected by resistance welding has been given. Instead of resistance welding, the method of connecting the collector and the tab portions to each other may be, for example, laser welding in which the connection is performed through projection of a high energy ray. An example of a collector, a metal member, and a resin member that are suitable for welding through projection of a high energy ray is given below.

FIG. 16 is a diagram of a prismatic secondary battery according to a first modification, corresponding to FIG. 15. As illustrated in FIG. 16, a slit 6 z is provided in each lead portion 6 c of the pair of lead portions 6 c of the positive electrode collector 6, and a slit 8 z is provided in each lead portion 8 c of the pair of lead portions 8 c of the negative electrode collector 8. By projecting a high energy ray, such as a laser beam, on the edge portions of the slit 6 z and the slit 8 z, the lead portions 6 c of the positive electrode collector 6 and the positive electrode tab portions 4 c are welded to each other and the lead portions 8 c of the negative electrode collector 8 and the negative electrode tab portions 5 c are welded to each other.

FIG. 17 is a cross-sectional view of the vicinity of the connection between the lead portions 6 c of the positive electrode collector 6 and the positive electrode tab portions 4 c of the prismatic secondary battery according to the first modification taken in the short direction of the sealing plate 2. A resin member 160 holds a first metal member 161 a and a second metal member 161 b in the surface on both sides thereof. The first metal member 161 a and the second metal member 161 b are each tabular and are disposed so as to be substantially parallel to the large-area side walls of the prismatic outer package 1. The resin member 160 includes a holding portion 160 a that holds the first metal member 161 a and the second metal member 161 b, a fitting recess 160 b, and a contact preventing portion 160 c. The fitting recess 160 b is fixed to the first fitting protrusion 2 c of the sealing plate 2. The first positive electrode tab group 4 x is welded to the first lead portions 6 c while the first positive electrode tab group 4 x is held between the first lead portions 6 c and the first metal member 161 a. Furthermore, the second positive electrode tab group 4 y is welded to the second lead portions 6 c while the second positive electrode tab group 4 y is held between the second lead portions 6 c and the second metal member 161 b. Note that similar to the positive electrode side, a resin member 180 that holds the first metal member and the second metal member is used in the negative electrode side.

Second Modification

FIG. 18 is a plan view of a negative electrode collector 108 before bending used in the prismatic secondary battery according to the second modification, and illustrates the surface thereof on the electrode body 3 side. The negative electrode collector 108 includes a collector body portion 108 a, a collector connection 108 b provided at the end (the end in the longitudinal direction of the sealing plate 2) of the collector body portion 108 a, and a pair of lead portions 108 c that extend from the two edge portions of the collector connection 108 b in the short direction of the sealing plate 2. The collector connection 108 b is bent with respect to the collector body portion 108 a so as to extend from the collector body portion 108 a towards the electrode body 3. In other words, the collector connection 108 b is bent with respect to the collector body portion 108 a towards the near side in FIG. 18. Subsequently, the pair of lead portions 108 c are bent with respect to the collector connection 108 b so as to extend in the longitudinal direction of the sealing plate 2. A through-hole 108 d into which the negative electrode terminal 9 is inserted is provided in the collector body portion 108 a.

Others

In the prismatic secondary battery 20 described above, the resin member 60 holding the metal member 61, and the resin member 80 holding the metal member 81 are disposed between the positive electrode terminal mounting hole 2 a and the negative electrode terminal mounting hole 2 b in the longitudinal direction of the sealing plate 2. However, the resin members holding the metal members may be disposed on the external side with respect to the positive electrode terminal mounting hole 2 a or the negative electrode terminal mounting hole 2 b in the longitudinal direction of the sealing plate 2. In other words, the resin member 60 holding the metal member 61 may be disposed between the end portion, among the two end portions in the longitudinal direction of the sealing plate 2, close to the positive electrode terminal mounting hole 2 a and the positive electrode terminal mounting hole 2 a in the longitudinal direction of the sealing plate 2. Furthermore, the resin member 80 holding the metal member 81 may be disposed between the end portion, among the two end portions in the longitudinal direction of the sealing plate 2, close to the negative electrode terminal mounting hole 2 b and the negative electrode terminal mounting hole 2 b in the longitudinal direction of the sealing plate 2.

In the prismatic secondary battery 20 described above, an example using the resin member 60 holding the metal member 61 and the resin member 80 holding the metal member 81 has been given. However, the positive electrode collector 6 and the positive electrode tab portions 4 c may be connected to each other without using the resin member 60 holding the metal member 61. Furthermore, the negative electrode collector 8 and the negative electrode tab portion 5 c may be connected to each other without using the resin member 80 holding the metal member 81.

In the prismatic secondary battery 20 described above, an example in which the connection between the lead portions 6 c of the positive electrode collector 6 and the positive electrode tab portions 4 c are disposed on the center side with respect to the positive electrode terminal 7 in the longitudinal direction of the sealing plate 2 has been given. However, the connection between the lead portions 6 c of the positive electrode collector 6 and the positive electrode tab portions 4 c may be disposed on the external side with respect to the positive electrode terminal 7 in the longitudinal direction of the sealing plate 2. Similarity, the connection between the lead portions 8 c of the negative electrode collector 8 and the negative electrode tab portion 5 c may be disposed on the external side with respect to the negative electrode collector 8 in the longitudinal direction of the sealing plate 2.

The method of connecting the positive electrode tab portions and the positive electrode collector to each other and the method of connecting the negative electrode tab portions and the negative electrode collector to each other are not limited to any method in particular and, for example, resistance welding, welding through projection of for example, a high energy ray such as laser ultrasonic welding, or ultrasonic welding may be used.

The form of the electrode body is not limited to any particular form and may be either a wound electrode body, a stacked electrode body, or an electrode body including a plurality of wound electrode bodies.

Desirably, an overcharge inhibitor, which generates gas when the battery becomes overcharged, is included in the battery. In a case of a nonaqueous electrolyte secondary battery, desirably, lithium carbonate is included in the positive electrode active material layers or cyclohexylbenzene or the like is included in the nonaqueous electrolyte. Furthermore, desirably, lithium phosphate is contained in the positive electrode active material layers. 

1. A prismatic secondary battery, comprising: an electrode body that includes a positive electrode plate and a negative electrode plate; an outer package that includes an opening and that houses the electrode body, a sealing plate that seals the opening; a terminal electrically connected to the positive electrode plate or the negative electrode plate; and a collector electrically connected to the positive electrode plate or the negative electrode plate, and the terminal, wherein the electrode body includes positive electrode tab portions and negative electrode tab portions that are stacked on a sealing plate side, and wherein a deformation plate provided in a conductive path between the positive electrode plate or the negative electrode plate and the terminal, the deformation plate being deformed when a pressure inside the battery becomes equivalent to or above a predetermined value, wherein the collector includes a collector body portion disposed on an electrode body side of the deformation plate, a collector connection that extends from an end portion of the collector body portion in a longitudinal direction of the sealing plate towards the sealing plate, and a lead portion that extends from the collector connection in the longitudinal direction of the sealing plate, wherein the collector body portion is connected to the deformation plate, wherein the positive electrode tab portion or the negative electrode tab portion is connected to the lead portion, and wherein the conductive path is cut off upon deformation of the deformation plate.
 2. The prismatic secondary battery according to claim 1, the lead portion is disposed substantially perpendicular to the sealing plate.
 3. The prismatic secondary battery according to claim 1, wherein the collector body portion includes a narrow width portion in an area adjacent to the collector connection, the narrow width portion having a width in a short direction of the sealing plate that is smaller than a width in the short direction of the sealing plate where the connection with the deformation plate is formed.
 4. The prismatic secondary battery according to claim 3, wherein a rate between the width of the portion of the collector body portion where the connection with the deformation plate is formed in the short direction of the sealing plate and a width of the collector body portion plate in the short direction of the sealing plate is 0.2 to 0.8.
 5. The prismatic secondary battery according to claim 4, wherein a length of the narrow width portion in the longitudinal direction of the sealing plate is three times or more with respect to a thickness of the narrow width portion.
 6. The prismatic secondary battery according to any one of claim 1, wherein a narrow width portion is disposed substantially parallel to the sealing plate.
 7. The prismatic secondary battery according to claim 1, wherein the collector connection includes a portion in which a length in a direction perpendicular to the sealing plate increases from a center towards an outer side of the collector connection in a short direction of the sealing plate.
 8. The prismatic secondary battery according to claim 1, wherein when the collector is unfolded, a slit is formed between the collector body portion and the collector connection, and wherein the slit is inclined 20 to 80° with respect to the longitudinal direction of the sealing plate.
 9. The prismatic secondary battery according to claim 1, wherein an end portion of the lead portion on the electrode body side is positioned on the electrode body side with respect to the end portion of the collector body portion on the electrode body side. 